The present invention relates to data networking and more particularly to systems and methods for providing fault tolerance to data networks.
The Internet and IP networks in general have become key enablers to a broad range of business, government, and personal activities. More and more, the Internet being relied upon as a general information appliance, business communication tool, entertainment source, and as a substitute for traditional telephone networks and broadcast media. As the Internet expands its role, users become more and more dependent on uninterrupted access.
To assure rapid recovery in the event of failure of a network link or node, so-called “Fast Reroute” techniques have been developed. In a network employing Fast Reroute, traffic flowing through a failed link or node is rerouted through one or more preconfigured backup tunnels. Redirection of the impacted traffic occurs very quickly to minimize impact on the user experience, typically in tens of milliseconds.
Fast Reroute, however, has been developed primarily for use in networks that employ MPLS (MultiProtocol Label Switching) Traffic Engineering. Rather than using conventional IP routing techniques where individual packets travel through the network following paths determined individually for each packet as it progresses through the network, MPLS Traffic Engineering exploits modern label switching techniques to build guaranteed bandwidth end-to-end circuits through a network of label switched routers (LSRs). MPLS Traffic Engineering networks are very useful to service providers who want to better utilize their network resources and provide quality of service guarantees to their customers. Such networks may be augmented with Fast Reroute capability by configuring backup tunnels in the form of LSPs in order to guarantee very fast traffic recovery in case of link or node failures. Depending on the particular variant of Fast Reroute employed, backup tunnels may be preconfigured for individual links or nodes, or for entire primary LSPs. Guaranteed backup protection may be provided by configuring the backup tunnels with guaranteed bandwidth. The configured backup tunnel bandwidth dictates the quality of service level of the rerouted Traffic Engineering LSPs during failures prior to reoptimization.
A problem arises in that Fast Reroute capability is highly desirable even in networks where MPLS Traffic Engineering has not been implemented. Fast Reroute capability may be required in an environment where the quality of service features provided by MPLS Traffic Engineering are not required. This is often the case for networks operating within an enterprise. What is needed are systems and methods for providing Fast Reroute capability to IP networks that do not employ MPLS Traffic Engineering end-to-end circuits.